The present invention relates to a sealing cap for openings of containers, in particular of motor vehicle radiators, comprising an inner cap element which provides at least one flow connection between the inside of the container and the outside of the container, and a valve arrangement for releasing and blocking the flow connection. The valve arrangement having a first valve body and a second valve body which can be moved back and forth between at least one release position and at least one blocking position, the first valve body being prestressed in the direction toward the inside of the container and being supported in this direction at a first seal seat on the inner cap element and at a second seal seat located radially within the first seal seat on the second valve body. The first valve seat can be lifted off the inner cap element when a first threshold value of the interior container pressure is exceeded, and can be lifted off the inner cap element and the second body, when a second, preferably a safety threshold value of the inner container pressure, is exceeded, each respectively by releasing a flow connection between the inside of the container and the outside of the container.
In connection with a known sealing cap of the type described in DE-41 07 525, a value cup with a radially outwardly extending flange is used as a first valve body, and as a second valve body a cylindrical sleeve concentrically enclosing the valve cup, which is also provided with a radially outwardly protruding flange, the flange seated on the cylindrical sleeve is shaped on the latter in the manner of a bead while forming a bulge. In the initial blocking position of the valve arrangement of the prior art, the cup valve, which is acted upon by a compression spring in the direction toward the container interior, is supported via a seal ring on the mentioned bulge of the second valve body. The cylindrical sleeve, on which a force also acts in is way in the direction toward the interior of the container, is also seated, with the interposition of a sealing ring, with its flange on a seal seat of the inner cap element. In the initial blocking position of the valve arrangement, a further sealing ring, which is corrected with the inner cap element, lies at a distance opposite the flange of the cylindrical sleeve in the direction of the container exterior. The three described sealing rings of the valve arrangement of the known sealing cap are indispensable for the desired two-stage pressure buildup of an overpressure prevailing in the interior of the container.
It is an object of the present invention to structurally simplify such a sealing cap.
In accordance with the present invention the second valve body is embodied as a component extending transversely with respect to the movement direction of the valve bodies, and has an opening located radially inside the second seal seat of the first valve body and is in flow connection with the inside of the container and to which a third seal is provided which is provided radially outside of the second seal seat of the first valve body in the direction toward the outside of the container on the inner cap element, against which it comes to rest via case of a third threshold value, located between the first and second threshold values of the inner container pressure, in the course of which it blocks a previously existing flow connection between the inside of the container and the outside of the container.
The described component, which is provided with an opening, represents a valve body of the simplest structural design. With an appropriate embodiment, in particular with an appropriate selection of material, a tight support, ie. without any additional sealing means, of the first valve body on the component constituting the second valve body will easily result. The use of such a component as the second valve body moreover provides the opportunity to accomplish the above mentioned blockage of the flow connection between the inside of the container and the outside of the container by means of the direct cooperation between the second valve body and the third seal seat.
In an advantageous manner, the component can be designed either as a radially guided deformable seal, or as a diaphragm, which can be deformed in the direction of movement.
The desired great operational dependability of the valve arrangement is achieved by means of the provision of a deformable seal radially extending with respect to the axial movement, or respectively the provision of a diaphragm guided on the inner cap element and/or the guidance of the component with the aid of a guide sleeve, which is either a part of the deformable seal or is equipped with the diaphragm, can be achieved by structurally simple means.
For aiding a tight contact between the first and second valve body of the sealing caps in accordance with the present invention, at least one spring is provided supported on the inner cap element which prestresses the component against the first valve body.
A preferred embodiment of the sealing caps in accordance with the present invention is distinguished by the provision of a guide sleeve designed with a stepped diameter and an axial section toward the first valve body as well as an axial section toward the bottom and a radial flange connecting the two axial sections on whose side facing the container the spring is supported.
A structurally extremely simple design in combination with the suitability of the second valve body for assuming a sealing function is achieved by means of a diaphragm designed as a rubber ring diaphragm.
The characteristics whereby the diaphragm is designed to have at least one fold are used to assure an even dependable operational behavior of the second valve body, and therefore of the entire valve arrangement.
Against the background that, in connection with sealing caps in accordance with the present invention, the equalization of an underpressure prevailing in the interior of the container should also be possible with structurally simple means, besides a two-stage buildup of an overpressure prevailing in the interior of the container, characterized in that the one of two partial valve bodies of the first valve body, which is supported from the direction of the inside of the container on the other partial valve body, is seated on the component on the outside of the container and sealingly covers the opening, wherein the other partial valve body is supported from the direction of the outside of the container on the first seal seat of the inner cap element and covers the partial valve body seated on the component with an opening, which is connected with the outside of the container, and wherein, by the action of an underpressure on the inside of the container, the partial valve body seated on the component can be lifted off the associated partial valve body, and in the course of this releases a flow connection between the inside of the container and the outside of the container.
In the interest of the simplest possible structural design of the entire arrangement, the partial valve body seated on the component has the second seal seat of the first valve body and is supported via it on the component. The partial valve body which is in contact with the component accordingly takes on a double function. It provides a tight connection between the first and second valve bodies both during the reduction of an overpressure prevailing in the interior of the container and during the equalization of a corresponding underpressure.
If required, the spring, by means of which the diaphragm is stressed against the first valve body, also takes on a double function, with the partial valve body seated on the component is lifted off the associated partial valve body counter to the action of the spring. For one, the spring sees to a tight contact of the diaphragm with the first valve body; it furthermore causes a tight contact of the first with the second valve body.